Epothilones are macrolide compounds that find utility in the pharmaceutical field. For example, epothilones A and B having the structures:                 epothilone A R═H        epothilone B R═Memay be found to exert microtuble-stabilizing effects similar to paclitaxel (TAXOL®) and hence cytotoxic activity against rapidly proliferating cells, such as, tumor cells or other hyperproliferative cellular disease, see Hofle, G., et al., Angew. Chem. Int. Ed. Engl., Vol. 35, No.13/14, 1567-1569 (1996); WO93/10121 published May 27, 1993; and WO97/19086 published May 29, 1997.        
Derivatives and analogs of epothilones A and B have been synthesized and may be used to treat a variety of cancers and other abnormal proliferative diseases. Such analogs are disclosed in Hofle et al., Id.; Nicolaou, K. C., et al., Angew Chem. Int. Ed. Engl., Vol. 36, No. 19, 2097-2103 (1997); and Su, D.-S., et al., Angew. Chem. Int. Ed. Engl., Vol. 36, No. 19, 2093-2097 (1997).
Analogs of the epothilones that have been found to have advantageous activity are represented by the following structure wherein Q, and R1 through R6 have the meanings given herein below. An improved synthesis for these analogs involving novel intermediates is provided in accordance with the present invention.